Both stress and emotion are complex psycho-physiological states involving characteristic neurological and physiological responses. Stress is characterized by loss of ability to appropriately respond to difficult emotional and physical conditions. It is characterized by a subjective strain, dysfunctional physiological activity, and deterioration of performance. Existing stress detection and classification methods use stress categories bases on different levels of difficulties that a given person has to deal with (ex. low level stress, moderate stress, high level stress).
Emotion represents a complex psycho-physiological state characterised by a person's state of mind and the way an individual interacts with an environment. It is a relatively short-term state that lasts from minutes to hours, and it is characterised by type of emotion (ex. happy, angry, sad, anxious) as well as intensity of emotion.
Depression is a psychiatric state that belongs to the group of affective (or emotional) disorders in which emotional disturbances consist of prolonged periods (days to months) of excessive sadness. Emotionally, depression sufferers experience lasting feelings of hopelessness, anger, guilt, desperation and loneliness often leading to suicidal thoughts.
Depressive disorders seriously affect social, emotional, educational and vocational outcomes. It is also the most common precursor of suicide. It is estimated that up to one in eight individuals will require treatment for depressive illness in their lifetime.
The prevalence of depression, the world's fourth most serious health threat in 1990,is expected to rise steadily. About 10% of the Australian population experience depression severe enough to require medical attention. Early diagnosis is extremely useful and can mean a minimal disturbance of typical functioning and development of social and academic skills.
Currently the diagnosis of depression is based on observations of behavioural patterns, and interviews with parents and their family members. This process is time consuming and the illness is usually recognised only once in advanced stages. The current diagnosis is qualitative and largely based on the personal skills, experience and intuitive judgment of a mental health practitioner. The number of highly skilled professionals is limited, and their availability is generally restricted to major towns and health centres. As a result, each year, thousands of cases of depression are not being diagnosed and left untreated, leading to potential suicides.
Acoustical properties of speech have been experimentally investigated as indicators of depression and suicidal risk. These investigations have included prosodic, vocal tract and glottal speech features such as fundamental frequency (FO), amplitude modulation, formants, power spectral density, vocal jitter, glottal flow spectral slope and cepstral features.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.